The analemma phenomenon: How does the sun draw the number 8 in the sky? | Jeddah Astronomy Society

The Jeddah Astronomical Society revealed details of one of the most astonishing and beautiful astronomical phenomena, the analemma , which documents the sun's apparent annual path across the sky. The society's president, Engineer Majid Abu Zahra, explained that this phenomenon traces a geometric shape resembling the number "8" in the sky, a sight that cannot be observed with the naked eye in a single moment, but rather requires patience and careful observation over an entire year.

The scientific secret behind the shape “8”

Abu Zahra explained that the formation of this unique path is not random, but rather the result of a complex and precise interaction between two main astronomical factors that govern the movement of our planet:

• The tilt of the Earth's axis: The Earth's axis of rotation is tilted at an angle of 23.5 degrees, which is the main reason for the occurrence of the four seasons and the change in the sun's height in the sky between summer and winter.
• Elliptical orbit: The Earth revolves around the Sun in an elliptical orbit, not a perfectly circular one, which causes the Earth's speed to change as it revolves; it speeds up when it is close to the Sun (perihelion) and slows down when it is far away (aphelion).

This variation in speed and position leads to a difference in the apparent position of the sun daily when observed at the same time, creating this distinctive curvature.

Time equation and astronomical context

The analemma is a visual representation of what is known in astronomy as the "equation of time," the difference between the time indicated by a sundial and the time indicated by a regular mechanical clock. Historically, astronomers were aware of this discrepancy in solar time, but it was only with the development of photography that humans could see this phenomenon, the analemma, as a single image. This allowed them to combine multiple photographs to illustrate how the sun precedes or lags behind clock time depending on the Earth's position in its orbit.

A photographer's guide to documenting the phenomenon

The head of the Jeddah Astronomical Society pointed out that documenting this phenomenon presents an enjoyable challenge for astronomy and photography enthusiasts, explaining the necessary technical steps:

• Fixed timing: The photos should be taken at exactly the same time (daily or weekly), for example, 10 am.
• Equipment: A digital camera securely mounted on a tripod to ensure the camera remains stable throughout the monitoring period.
• Shooting settings: Use a solar filter to protect the sensor, with a high shutter speed (between 1/1000 and 1/8000 seconds), a narrow aperture (f/7.1 to f/11), and low light sensitivity (ISO 100-200).

He confirmed that starting the monitoring from January 21, 2026 will allow photographers to complete the full cycle by January 2027, to obtain the complete “8” shape.

The scene in the Kingdom's sky is different

Abu Zahra noted that the shape of the analemma varies depending on the observer's geographical location on Earth. In the skies of Saudi Arabia, the shape appears clearly with a vertical elongation, high above the horizon and less horizontally extended. In other northern countries, such as Egypt and Lebanon, the shape tends to be lower and closer to the horizon in winter. In southern regions, such as Yemen, the shape appears more slanted and narrower.

Scientific implications that go beyond visual beauty

The analemma is not only a celestial work of art, but also a tangible observational testament to the Earth's spherical shape and dynamic motion. The upper part of the figure eight represents the summer solstice (the longest day of the year), while the lower part represents the winter solstice (the shortest day). This phenomenon is an excellent educational tool for simplifying concepts of celestial mechanics for students and enthusiasts, emphasizing that the sky is not a static canvas, but a constantly moving and changing stage.